Honestly, it may be tough to tell at this point - I would say either the heatsink is faulty (heatpipes crimped at all? bent anywhere? dents/etc.?) or the contact pressure isn't high enough (this is of course assuming everything else is good - installation/thermal paste/etc.). I would see if you can find other software to "get a second opinion" on the CPU temps (open hardware monitor may work as well, coretemp, etc.). Once that's verified then remove the heatsink, clean the surfaces (preferably with some thermal paste remover) and reapply thermal paste and the EVO. Can you try the stock cooler as well? If you get better temps with the stock cooler (which you should at idle, depending on ambient temps), then you can begin to suspect...